<template>
  <div ref="scrollContainer" class="scroll-container" @wheel.prevent="handleScroll">
    <div ref="scrollWrapper" :style="{ left: left + 'px' }" class="scroll-wrapper">
      <slot />
    </div>
  </div>
</template>
<script>
const padding = 5 // tag's padding

export default {
  name: 'ScrollPane',
  components: {},
  props: {},
  data() {
    return {
      left: 0,
    }
  },
  computed: {},
  watch: {},
  created() {},
  mounted() {},
  methods: {
    handleScroll(e) {
      const eventDelta = e.wheelDelta || -e.deltaY * 3
      const $container = this.$refs.scrollContainer
      const $wrapper = this.$refs.scrollWrapper
      const containerWidth = $container.offsetWidth
      const wrapperWidth = $wrapper.offsetWidth

      if (eventDelta > 0) {
        this.left = Math.min(0, this.left + eventDelta)
      } else {
        if (containerWidth - padding < wrapperWidth) {
          if (this.left >= -(wrapperWidth - containerWidth + padding)) {
            this.left = Math.max(this.left + eventDelta, containerWidth - wrapperWidth - padding)
          }
        } else {
          this.left = 0
        }
      }
    },
    moveToTarget($target) {
      const $container = this.$refs.scrollContainer
      const containerWidth = $container.offsetWidth
      const targetLeft = $target.offsetLeft
      const targetWidth = $target.offsetWidth

      if (targetLeft < -this.left) {
        // tag in the left
        this.left = -targetLeft + padding
      } else if (
        targetLeft + padding > -this.left &&
        targetLeft + targetWidth < -this.left + containerWidth - padding
      ) {
        // tag in the current view
        // eslint-disable-line
      } else {
        // tag in the right
        this.left = -(targetLeft - (containerWidth - targetWidth) + padding)
      }
    },
  },
}
</script>
<style scoped lang="scss">
.scroll-container {
  white-space: nowrap;
  position: relative;
  overflow: hidden;
  width: 100%;
  .scroll-wrapper {
    position: absolute;
  }
}
</style>
